Connecting solar controller to inverter or converter feeds

[Fisherguy]

I have a PD9280 and a Xantrex 600 watt inverter up front in our trailer under the front sofa. Each one is connected to my golf cart batteries with it's own 4ga cables, fuses are on the A frame in a weatherproof box, 100 amp fuse for the PD, 80 amp for the inverter.

Now I'm adding solar panels (3-120'S) and a Tristar 45 watt PWM controller; I don't want to remove the trailer underbelly to run more cables to the battery for the controller, so do you think it's ok to connect the controller to the 4ga going to the inverter, or should I change the wiring so the inverter is fed by the same 4ga going to the PD converter allowing me to connect the controller to the 4ga that used to go to the inverter? (Hopefully you know what I mean?)
( ... or am I worrying too much) 😉
Thanks

[pianotuna]

Flat install will reduce the effective wattage by perhaps as much as 25%. Since it is a pwm controller see BFL's figure for amps into the battery bank.

Fisherguy wrote:

pianotuna wrote:
He will never see 20 amps of solar.

Why not?

[CJW8]

This is the was I am getting ready to do mine as well. Electrically it isn't that much different than connecting to the battery. Your connection point is just at a different end of a piece of cable and in my case the inverter cable is fused to 250 amps. The most I have ever seen on the inverter is 160 amps and I am installing a 30 amp controller that will occasionally see 30 amps.

[Fisherguy]

MEXICOWANDERER wrote:
Confucius say

"Not lower river

Raise bridge"

Yank 100-amp fuse
Push in 120-amp fuse

... or use the inverter feed....

[BFL13]

smkettner wrote:
If the solar is putting out 20 amps there is probably no power in sight.
If the PD actually is going at 80 amps there has been no solar for some time.

Connect where you like. #4 is good for 140 amps and the chance of popping a fuse is about zero.

ISTR he has a 100a fuse on that path. Might not be so easy to up the fuse size depending on fuse holders etc. No idea.

[MEXICOWANDERER]

Confucius say

"Not lower river

Raise bridge"

Yank 100-amp fuse
Push in 120-amp fuse

[Fisherguy]

OK, I'm connecting the controller outputto the inverter input like I was originally intending to do.
Consensus says this is ok to do.

Thanks guys.

[BFL13]

pianotuna wrote:
He will never see 20 amps of solar.

Amps will only go one way if the inverter is drawing more than the solar panels are producing.

I think he is using battery voltage sense wires.

........

Yes he is. Three 120s is 360w at three times 7.6a aimed (22.8a) but his are flat so will be less depending on location and time of year how much less.

I am just having mental problems 🙂 seeing the voltages at each end of the wire what with the controller doing its PWM in Absorb, the load with voltage drop at how many amps, and the actual battery voltage so you get "net" flow from high to low. But this isn't about my brain's weaknesses, Fisherguy wants to know which way to wire his set-up.

[Fisherguy]

pianotuna wrote:
He will never see 20 amps of solar.

Why not?

[time2roll]

If the solar is putting out 20 amps there is probably no power in sight.
If the PD actually is going at 80 amps there has been no solar for some time.

Connect where you like. #4 is good for 140 amps and the chance of popping a fuse is about zero.

[pianotuna]

That would depend on the frequency of the pulses. I doubt you will notice anything. Any such "noise" would be introduced even if the controller charge line was direct to the battery bank.

Lead acid batteries are sometimes referred to as accumulators--which is another word for capacitor. There are lots of old converters still in use which use the battery to 'smooth' their output.

BTW my pd converter is quite noisy to the point where I can not use it and listen to AM radio in the cab of my class C. The Blue Sky makes no such (audible) noise.

Alternators also are 'noisy'.

Fisherguy wrote:
If the PCM controller is basically putting out a square wave as it pulses is there a chance it would cause noise on the inverter input? If they were on separate battery feeds would the battery help 'filter' the pulses?
... or am I thinking too much again? 😄

[12thgenusa]

BFL13 wrote:
I am not clear on what happens if the amps are opposing direction on the same wire. What would the solar controller think is going on if it is trying to pass 20 amps to the battery along a wire that had 10 amps coming the other way to the inverter?

Won't ever happen. The solar will always supply the load before it supplies the battery. Electrical current is just like water current - always flows down hill.

[MrWizard]

Fisherguy wrote:

MrWizard wrote:
Connect it to the wires for the inverter
The inverter is never going to draw more than what it always use,s
If part of that power amps is from the solar , that just less from the batteries, very unlikely to do an over load on the inverter circuit

If the PCM controller is basically putting out a square wave as it pulses is there a chance it would cause noise on the inverter input? If they were on separate battery feeds would the battery help 'filter' the pulses?
... or am I thinking too much again? 😄

over thinking
same wires...separate wires.. the battery is still a giant filter capacitor on the circuit

[pianotuna]

He will never see 20 amps of solar.

Amps will only go one way if the inverter is drawing more than the solar panels are producing.

I think he is using battery voltage sense wires.

BFL13 wrote:


If he has the 80amp PD going as well as say 20 amps of solar, he would equal his 100 amp fuse on that path. If he passed the solar along the inverter wires it would only add up to the solar amps on that 80 amp fuse there.

I am not clear on what happens if the amps are opposing direction on the same wire. What would the solar controller think is going on if it is trying to pass 20 amps to the battery along a wire that had 10 amps coming the other way to the inverter?

[Fisherguy]

Barry, like I said above, I don't think current flows both directions, I said
"so I'm thinking when watching TV the inverter draws about 8 amps, if the solar controller is putting out 20 amps the net flow would be 20 - 8 = 12 amps TO the batteries."
Isn't that right guys?